The description relates to assembling technology for semiconductor chips and more particularly, to a semiconductor package with improved mechanical stability and thermal characteristics.
A sheet of wafer usually includes several dozens or several hundreds of chips with electrical circuits printed by a semiconductor manufacturing process. The chips on the wafer cannot operate without an external electric power supply. In addition, the microelectronic circuits are readily damaged by external impacts or surges. A known assembling technology for packaging such chips, e.g., forming a semiconductor package, provides the chips with mechanical stability. In applicable products, the semiconductor package provides electrical connections to the chip for supplies of power and signals shielded by plastic housings against external impacts or surges across various environments.
Generally, semiconductor packages can be classified into resin sealing packages, tape carrier packages (TCP), glass sealing packages, and metal sealing packages, etc. These semiconductor packages are further classified into insertion types and surface mounting types in accordance with mounting methods. Typically employed as the insertion type are a dual in-line package (DIP) and a pin grid array (PGA), etc. Typically employed as the surface mounting type are a quad flat package (QFP), a plastic leaded chip carrier (PLCC), a ceramic leaded chip carrier (CLCC), and a ball grid array (BGA), etc.
In a conventional semiconductor package, a semiconductor chip is positioned on a chip-accommodating space of a circuit board having a structure that has wire patterns and the space capable of mounting the chip thereon and offering the chip electrical connections by means of the wire patterns. The circuit board, on which the semiconductor chip is attached, has been being made of an organic material. The organic material is widely used as the circuit board because its wire pattern can be easily formed with a known process and an inexpensive manufacturing cost as well.
However, since the circuit board is formed of the organic material and in direct contact with the semiconductor chip, thermal characteristics of the semiconductor package degrade. In other words, the organic circuit board may be unable to dissipate a high temperature generated by the semiconductor chip and the circuit board.
Therefore, packages using ceramic materials having improved thermal characteristics have been used. However, forming the wire pattern on the ceramic material requires high manufacturing cost in comparison with forming the wire pattern on the organic material. In addition, the ceramic material lacks sufficient mechanical stability for the semiconductor package since it is sensitive to a high external pressure.
To solve problems concerned with the mechanical stability of the ceramic material, a metal PGA package using a metal circuit board has been proposed. The metal PGA package is disclosed in U.S. Pat. No. 5,103,292, entitled “METAL PIN GRID ARRAY PACKAGE.” Insertion holes corresponding to the number of conductive pins for connecting to another external circuit board are formed at a metal plate located under the circuit board, and insulating material is filled into the respective microscopic insertion holes. However, it is difficult to form the many microscopic insertion holes needed to correspond to the number of the conductive pins on the metal plate. As a result, the proposal offered a complicated process and high manufacturing cost.